The objective of this proposal is to characterize and to quantitate those glycoproteins which are synthesized and released by human breast cancer surgical specimens. Special emphasis is given to gp48 and related glycoproteins, which appear to be released in greater abundance from malignant than benign specimens. To achieve this, we propose to biosynthetically label glycoproteins with 3H- or 14C- carbohydrate precursors using either established cell lines or organ cultures of human breast cancer surgical specimens. The labelled glycoproteins are characterized by two-dimensional gel electrophoresis. Those components which are related to known serum glycoproteins are immunoprecipitated and their antigenic relationships are further investigated. Glycoproteins which appear antigenicly unique will be purified from surgical specimens, using the biosynthetically labelled glycoproteins as tracers. Their relationship to normal membrane components derived from breast epithelial cells will be investigated using human milk fat globular membranes. The purified glycoprotein will be used for the production of immune antisera or monoclonal antibodies. After appropriate adsorptions, the specific antisera will be used to establish a quantitative immunoassay using either a nonradioactive immunodiagnostic procedure with rate nephelometry or a radioimmunoassay with the 125I labelled glycoprotein.